In most oil well completions, a centralizer is used to center the screen within the casing. When gravel is introduced between the casing and screen, the centralizer ensures that the gravel is of even radial thickness in the annular space. It is important in the installation of the screen that the centralizer be axially fixed in place. A centralizer which is not fixed in place will tend to slide along the screen and string of pipe if its projecting ears become hung up within the casing, such as on a casing joint. Such movement of the centralizer with respect to the screen will negate the centralizer's function. The common clamp-on centralizer is susceptible to this failure. The welded-in-place centralizer avoids the problem, but has other disadvantages. The clamp-on centralizer offers ease of installation, flexibility of axial location, and requires no specialized equipment such as welders.